The present invention relates to an adaptive autopilot and, more specifically, to an adaptive autopilot for a reentry type vehicle, wherein size and weight constraints are of paramount importance.
Some strategic missile systems are required to be targetable to hardpoint installations, target-defense systems, and relocatable and moving targets. Delivery of payloads with extreme accuracy requires "smart" reentry vehicles to sense while in flight and then home onto a selected target. These requirements necessitate improved accuracy of advanced maneuvering reentry vehicles with a desired reduction of weight, cost and on-board power demand for the reentry navigation, guidance and control system.
Prior reentry vehicle control systems have used a high performance hydraulic actuator, having a piston for moving aerodynamic control surfaces. Such a system requires substantial power, is heavy, and may leak during storage in the interval between installation at a launch site and actual use. Preventive maintenance may require periodic inspection and testing to ensure that such leakage has not occurred. In addition, these systems typically use an outer control loop to control maneuver acceleration and an inner control loop to damp vehicle airframe oscillations. A control signal is available at the output of the inner loop for energizing the actuator. However, the inner and outer control loops of prior systems do not provide an especially accurate control signal which in combination with the large hydraulic actuator leads to a "brute force" type of system.
It would be desirable to have a system that could estimate the operating dynamic characteristics, or parameters, required by the reentry vehicle, or airframe, in response to actual status parameters of the vehicle so that appropriate settings of the aerodynamic control surfaces could be achieved and maintained for obtaining the desired flight path and performance with a minimal amount of intervention from the actuator for attaining the desired dynamic operating characteristics. The system also should be able to be implemented to minimize its weight and size. In addition it would be desirable to eliminate the need for a heavy hydraulic actuator.
Accordingly, it is an object of the present invention to provide an adaptive autopilot or control system for a reentry type vehicle wherein the weight and size of the system is reduced from those of prior systems.
Another object of the present invention is to provide an adaptive autopilot or control system for a reentry type vehicle wherein the system does not rely on hydraulic actuation for moving aerodynamic control surfaces.
Yet another object of the present invention is to provide an adaptive autopilot for a reentry type vehicle wherein the system provides more computation for estimating dynamic aerodynamic operational parameters in response to status parameters, thereby enabling the size and high performance requirements of the actuator to be reduced.